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Nematode Constraints of Chickpea and Pigeonpea Production 61 the Semiarid Tropics Chickpea (Cicer arietinsrrn L.) and pigeonpea (Cajanus cajan (t.) Millsp.

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Production of cool season food legumes can be severely limited by nematode attack. Symptoms are yellowing, wilting, stunting, decreased biomass and seed yield. The most damaging nematodes are root-knot (Meloidogyne spp.), cyst (Heterodera spp.), root-lesion (Pratylenchus spp.) and stem (Ditylenchus dipsaci). Integrated control is required where profit margins and environmental considerations preclude the use of nematicides. The main factors for effective integrated control are: correct diagnosis of the nematode problems, use of tolerant and resistant cultivars of the main crops, rotation with resistant cultivars of other crops, fallowing, control of weed hosts, choice of sowing time, soil amendment, and sanitation. Present knowledge and future requirements for effective integrated control of the main nematode diseases of each of the cool season food legume crops are discussed. 491 R. Knight (ed.), Linking Research and Marketing Opportunities for Pulses in the 2l st Century, 491~566.

Low-temperature stress (LTS) drastically affects vegetative and reproductive growth in fruit crops leading to a gross reduction in the yield and loss in product quality. Among the fruit crops, temperate fruits, during the period of evolution, have developed the mechanism of tolerance, i.e., adaptive capability to chilling and freezing when exposed to LTS. However, tropical and sub-tropical fruit crops are most vulnerable to LTS. As a result, fruit crops respond to LTS by inducing the expression of LTS related genes, which is for climatic acclimatization. The activation of the stress-responsive gene leads to changes in physiological and biochemical mechanisms such as photosynthesis, chlorophyll biosynthesis, respiration, membrane composition changes, alteration in protein synthesis, increased antioxidant activity, altered levels of metabolites, and signaling pathways that enhance their tolerance/resistance and alleviate the damage caused due to LTS and chilling injury. The gene induction mechanism has been investigated extensively in the model crop Arabidopsis and several winter kinds of cereal. The ICE1 (inducer of C-repeat binding factor expression 1) and the CBF (C-repeat binding factor) transcriptional cascade are involved in transcriptional control. The functions of various CBFs and aquaporin genes were well studied in crop plants and their role in multiple stresses including cold stresses is deciphered. In addition, tissue nutrients and plant growth regulators like ABA, ethylene, jasmonic acid etc., also play a significant role in alleviating the LTS and chilling injury in fruit crops. However, these physiological, biochemical and molecular understanding of LTS tolerance/resistance are restricted to few of the temperate and tropical fruit crops. Therefore, a better understanding of cold tolerance’s underlying physio-biochemical and molecular components in fruit crops is required under open and simulated LTS. The understanding of LTS tolerance/resistance mechanism will lay the foundation for tailoring the novel fruit genotypes for successful crop production under erratic weather conditions.